1. Field of the Invention
The present invention relates to a speaker, particularly to a piezoelectric panel speaker and an optimal method of designing the same.
2. Description of the Related Art
Piezoelectric materials have found applications in many areas of sensors and actuators since the discovery of piezoelectricity by Curie brothers a century ago. However, it was not until recently that designers started to explore the possibility of using it as a driving mechanism for panel speakers, e.g., Taiyo Yudan, Murata, NXT, etc. One advantage of such devices is that the electroacoustic efficiency of piezoelectric materials is considerably higher than their voice-coil counterpart.
In the panel speaker of the prior art, piezoelectric materials are directly attached to a diaphragm, and the diaphragm is bound with a surrounding frame disposed on a case of the panel speaker. For consolidating the whole structure, the diaphragm supported by the piezoelectric materials is bound very tightly with the surrounding frame. Therefore, the structure of the panel speaker does not easily collapse. The performance of the prior art panel speaker within the low frequency range is not satisfactory due to the fact that the stiffness of the panel speaker is hard. Thus, the piezoelectric panel speaker is applied to a treble unit speaker such as a buzzer.
Lee and White applied additional layers onto cantilever acoustic devices to reduce the fundamental frequency and improve acoustic output. Woodard used tailoring vibration response, vibration topography, acoustic chamber and tailoring damping to improve the acoustic performance. Chu et al. optimized the shape of the piezoelectric plate to reduce the fundamental frequency. Various approaches such as the genetic algorithm and Taguchi method dealing with optimal design were reported in writings. However, up to now, there are no panel speakers effectively improving acoustic output at lower frequency.
In view of the problems and shortcomings of the prior art, the present invention provides a new configuration of piezoelectric panel speaker and an optimal design method of designing the same, which discloses a new piezoelectric panel speaker structure and a simulated platform for frequency response, so as to solve the afore-mentioned problems of the prior art.